Counterflow fireplace

ABSTRACT

The double-walled fireplace is described which is adapted to be connected to a counterflow chimney arrangement designed to introduce cold air into the fireplace through an outer duct while the heated air is drawn out through an inner duct and discharged to the atmosphere simultaneously with flue gases from the firebox. At the point of attachment of the chimney to the firebox, a diaphragm or baffle assembly is provided which directs the cold air down the sides of the firebox. By providing suitable baffling on one side of the front and the opposite side at the rear, the air flowing down one side can be made to pass up the firebox, and the cold air from the other side can be made to pass up the rear wall of the firebox. In order to accommodate different fireplace configurations it is possible to modify the baffle structure so that different flow patterns will occur.

United States Patent [72] lnventor [Z1 1 App]. No. [22] Filed [45]Patented Walter C. Carson PA). Box 1381,8avannah, Ga. 31401 846,911

Aug. 1, 1969 Aug. 24, 1971 [54] COUNTERFLOW FIREPLACE PrimaryExaminerCharles J. Myhre Attarney-Cushman, Darby & Cushman ABSTRACT: Thedouble-walled fireplace is described which is adapted to be connected toa counterflow chimney arrangement designed to introduce cold air intothe fireplace through an outer duct while the heated air is drawn outthrough an inner duct and discharged to the atmosphere simultaneouslywith flue gases from the firebox. At the point of attachment of thechimney to the firebox, a diaphragm or baffle assembly is provided whichdirects the cold air down the sides of the firebox. By providingsuitable baffling on one side of the front and the opposite side at therear, the air flowing down one side can be made to pass up the firebox,and the cold air from the other side can be made to pass up the rearwall of the firebox. In order to accommodate different fireplaceconfigurations it is possible to modify the baffle structure so thatdifferent flow patterns will occur.

PATENTEU AUG24|97| SHEET 3 BF 4 F/if 5 0X L m ME 5 M 3 3 OW QM MCOUNTERFLOW FIREPLACE This invention relates to fireplace constructionand in particular to a fireplace assembly which is prefabricated to beinstalled into the building of which it is to become a permanent part.

A major problem facing those designing fireplace assemblies of theabove-mentioned type is to provide a fireplace in which the exteriorsurfaces are sufficiently cooled so that the temperature of thefireplace will not endanger the surrounding structure. Furthermore, thefireplace must be designed-so that it will not direct a significantamount of heat into the room in which it has been placed so as not to beuncomfortable when used with a central heating system.

In Us Pat. No. 2,821 ,975to Robert K. Thulman, a fireplace 7construction is described which circulates cool air around the fireboxand draws off the heated air. This latter construction provides aplurality of thermosyphonic paths to maintain safe temperatures on thesurface of the outer casing of the fireplace unit. This patentedconstruction is, however, unduly complex in that at least two concentriccasings must be provided around the firebox in order to paths forairflow. This results not only in a complex assembly, but one of extremeweight and bulk.

It is therefore an object of this invention to provide a fireplaceassembly which is of simple construction and uses only a single housingaround the firebox while providing the needed paths for cooling airflow.

It is another object of this invention to provide a baffle system for afireplace construction having only a single housing around the fireboxin which said baffles properly direct cool airflow from a cold air ductand in which others of said baffles direct the heated air into a hot airduct to be expelled.

The aforementioned and other objects may be obtained in a fireplaceassembly constructed according to the principles of this invention inwhich a single housing surrounds the firebox and the dome structureextending from the firebox to the chimney. The double-walled fireplaceassembly connects to a counterflow chimney having an annular cold airduct and an annular hot air duct coaxial therewith. The cold air isdrawn down into the fireplace assembly, and the heated air is drawn upthrough an inner casing and discharged to the atmosphere simultaneouslywith flue gasses from the firebox. At the point of attachment of thechimney to the dome structure of the firebox, the cold air is directedby means of suitably constructed and placed baffles down the side wallsof the firebox and up the rearwall of the firebox. A baffle is providedto direct the heated air from the rear wall into the heated air duct.Baffles are provided to direct a portion of the cool air to a front wallof the dome structure of the fireplace, and a baffle is provided fordirecting the heat from the front portion of the fireplace up into theheated air duct. This airflow pattern can be modified by altering thebaffle structure around the dome of the firebox so that, for example,the airflow can be diverted making it flow down the front and back upthe side. Therefore, the exterior temperature of the fireplace assemblyconstructed according to the principles of this invention is maintainedat an acceptable level while obviating the need for a complex and bulkystructure.

BRIEF DESCRIPTION OF THE DRAWINGS The invention may be best understoodby reference to the specification hereinbelow and the drawings in which:

F IG. 1 is a front elevation of a preferred embodiment of the fireplaceassembly constructed according to the principles of this invention;

FIG. 2 is a side elevational view of the preferred embodimentillustrated in FIG. 1;

FIG. 3 is a rear perspective view of the preferred embodimentillustrated in FIG. 1 with the sidewalls and the rear wall of thehousing removed;

FIG. 4 is a top elevational view of the preferred embodiment illustratedin FIG. 1;

provide the necessary FIG. 5 is a fragmentary front perspective view ofthe preferred embodiment illustrated in FIG. 1 in which the front walland a sidewall of the housing have been removed;

FIG. 6-9 are sectional plan views of an open front fireplace constructedaccording to the principles of this invention illustrating the variousairflow patterns which may be realized in a fireplace constructionutilizing this invention;

FIGS. 1013 are sectional plan views of an open end fireplace, which is afireplace open on two adjacent sides, constructed according to theprinciples of this invention illustrating the various airflow patternswhich may be realized using this invention; and

FIGS. 14-17 are sectional plan views of a fireplace open on two oppositesides constructed according to the principles of this inventionillustrating the various airflow patterns which may be realizedutilizing this invention.

DETAILED DESCRIPTION OF THE DRAWINGS FIGS. 1-5 in which like numeralsrefer to like elements illustrate the structural details and the airflowpatterns of a fireplace constructed according to the principles of thisinvention of the type which has a single horizontal opening forreceiving combustibles. The fireplace assembly is generally indicated bythe numeral 10. A firebox generally indicated as 16 is made up of a basemember 20, sidewalls 18 and 19'and a rear wall 22 which extendsvertically upward from the base member 20 until a shoulder 21 is reachedfrom whence the rear wall 22 tapers upwardly and inwardly. The fireboxopening is surrounded by flat elongated frame members 14.

The upper portion of the firebox 16 communicates with a dome structuregenerally indicated as 30 which in turn communicates with a chimney flue32. The dome structure 30 is formed from a rear wall 31, a front wall33, and baffles 35 and 36. The rear wall 31 of the dome structure 30, asbest shown in FIG. 3, extends upwardly from the upper end of rear wall22 of the firebox 16 to a cover member 29 through which the chimney flue32 is connected to the dome structure and thereby to the firebox bymeans of a circular opening centrally disposed therein. The front wall33 of the dome structure 30 extends upwardly from the horizontal openingof the firebox to the cover member 29. As will be described in greaterdetail hereinbelow, the walls 33 and 31 form baffles conducting theheated air upwardly and away from the fireplace assembly. Baffles 35 and36 form the sidewalls of the dome structure 30, but these walls orbaffles extend upwardly beyond the cover member 29, while taperinginwardly, to a cover member 37. A circular opening is centrally disposedin cover member 37 to allow a cylindrical casing 34 which is concentricwith but of a greater diameter than chimney flue 32, to passtherethrough. The casing 34 extends downwardly only so far as to passthrough cover 37. The annular space between chimney flues 32 andcylindrical casing 34 forms an inner annular duct 40 through which theheated air is expelled to the atmosphere.

A housing 12 entirely surrounds the firebox 16 and the dome structure30. It will be noted that the portion of the housing 12 which surroundsfirebox 16 is substantially rectangular while the walls of the housing12 surrounding the dome structure 30 taper inwardly forming awedge-shaped configuration. The housing 12 is spaced from the walls ofthe dome structure 30 and the firebox 16 forming therewith thepassageways through which the cold air and the heated air circulatearound the firebox and dome assembly. A cover member 13 forms the top ofthe housing 12. Centrally disposed in cover member 13 is a circularopening of a diameter which will allow it to receive a cylindricalcasing 38 which extends only so far as to go through cover 138 and whichis concentric with flue 32, but of a greater diameter than cylindricalcasing 34. Thus, an annular outer duct 42 is formed between the casing34 and 38. It is through this outer duct 42 that the cold air forcooling the fireplace assembly 10 is introduced therein.

The housing walls 52 and 54 which are adjacent the dome structure walls31 and 33, respectively, are inclined at an angle which allow them to bejoined with cover members 13 and 37 but not with cover member 29,because walls 31 and 33 are inclined inwardly at a greater angle thanthe angle of incline of walls 52 and 54 and cover member 29 is narrower.Thus, passages extending from the sides of annular ducts 42 passing downbaffles 35 and 36 to the sides of firebox 16 are formed. The rear wall52 of housing 12 and baffle 31, which is a rear wall of the domestructure 30, form a passage extending downwardly from the annular ducts40 to the area adjacent the rear wall 22. Likewise, front baffle 33,which forms the front wall of the dome structure 30 and which extendsdownwardly from the front portion of annular ducts 40 forms along withfront wall 54 of the housing 12 a passageway from the upper frontportion of the firebox 15 and the surfaces formed by the rear surfacesof vertical frame members 14 to the annular duct 40. The base of memberof firebox 16 is mounted on legs 15 which extend from the base member 20to the bottom of housing 12 forming therebetween a gap 17 which providesa passageway for air flow beneath the firebox. as shown in FIG. 5, anupright baffle 138 is provided which extends downwardly from front torear within the duct defined by the baffle 35 and the wall of housing 12adjacent the baffle. Baffle 138 directs a portion of the cool airproceeding down baffle 35 to the front wall 33 of the fireplace domestructure 30. A baffle similar to baffie 138 may be provided on theopposite side of the duct at baffle 36. A bafile 39 extending beneathbase member 20 directs a portion of the airflow thereunder to rear wall22.

DESCRIPTION OF OPERATION After a fire has been built in firebox 16, asis generally the case with fireplaces having a single horizontalopening, the sidewalls 18 and 19 of the firebox will be at a lowertemperature than rear wall 22, base plate 20 and the front wall 33 ofthe dome structure. With this temperature relationship of the fireboxwalls it is desirable to direct the incoming cold air downward along thelower temperature walls allowing the heated air to be drawn upwardlyalong the walls which are at a higher temperature. This is accomplishedby utilizing the principles of this invention to construct a fireplaceassembly of only double-walled construction and providing theappropriate bafiles to properly direct the air to and from a counterflow chimney, thus, utilizing the counterflow principle for cooling theexterior surfaces of the fireplace. This should be contrasted with theprior art devices in which triple-walled construction was used to employthermosyphonic movement of air around the exterior surfaces of thefireplace resulting in a complex, bulky structure.

In operation the cold air is drawn downwardly through outer annular duct42 and directed by the side baffles 35 and 36 downwardly along thesidewalls 18 and .19 of the firebox. As mentioned above, baffie 138shown mounted adjacent side baffle 35 directs a portion of the incomingcold air along the forward wall 33. A portion of the airstreamdescending adjacent to baffle 36 is directed back up the front wall 33in a similar manner, as shown by the arrow in FIG. 5. The air directeddown the sidewalls of the firebox will proceed underneath base plate 20and will be drawn upwardly across rear wall 22 and the rear surfaces ofvertical frame members 14. The air directed to the front portion of thefireplace assembly will proceed upwardly along inclined forward wall 33of the dome structure and enter inner annular duct 40. The heated airfrom rear wall 22 is directed upwardly along the rear wall 31 of thedome structure into the inner annular duct 40. Therefore. the flowpattern in this embodiment is basically one of having cold air directeddown the sides of the fireplace and heated air up the front and backwalls.

The fireplace assembly constructed as described hereinabove may beplaced in a building wall which provides the necessary clearances. Thefirebox may be held in place by blocking with stud wallplates ormoulding, or it can be nailed or screwed in place through the holespunched in either side of the fireplace frame. Any conventionalwall-covering material may be applied to the studs providing it does notextend within approximately 2 inches of the sides of the fireplaceopening, or within about 4inches from the top thereof. The chimney maybe installed in the conventional manner making sure that the necessaryclearances are provided between the chimney structure and thesurrounding wall and floor material.

FIGS. 617 are sectional plan views of various fireplace configurationsdescribing the various airflow patterns which may be caused to takeplace by constructing the particular fireplace according to theprinciples of this invention. That is, by providing the particularfireplace configuration with the proper baffles, and by properly placingand directing those baffles, the illustrated flow pattern will be theresult. The choice of which baffle configuration to use will depend uponwhich walls are desired to be kept at a lower temperature with respectto the other walls.

FIGS. 6-9 illustrate the flow patterns which may be caused to occur inan open front fireplace like the one described hereinabove as apreferred embodiment of the invention. F IG. 6 is a diagram of the flowpattern taking place in the fireplace assembly described hereinabovewith reference to FIGS. 1-5. The baffies direct the cold air down theside of the fireplace and up both the front and the back. FIG. 7demonstrates a variation of the flow pattern in the same type offireplace wherein air is caused to move down the sides of the fireplace,but the air from one side moves only up the backwall while the air fromthe other side moves only up the front. FIG. 8 illustrates an open frontfireplace in which the airflow pattern of FIG. 6 is just reversed. Inthis case the air is caused to move down the front and back and up thesidewalls. FIG. 9 is a flow pattern which is just the reverse of theflow pattern of FIG. 7, and in this case the air moves down the frontand back, but the air from the back moves only up one side and the airfrom the front moves up only the other side.

FIGS. 10-43 illustrates the flow patterns which may be caused to occurin the fireplace having two adjacent sides open, and indicated by thelegend openings and the arrows. In these figures the same sequence offlow patterns as was illustrated in FIGS. 6 9 may be caused to takeplace.

FIGS. 14-17 illustrate the use of this invention in conjunction with asee through fireplace or one in which two opposite sides are open. Thesequence of the flow pattern in these FIGS. is the same as the sequenceillustrated in FIGS. 69.

The embodiments described hereinabove are only exemplary, and it will beapparent to those skilled in the art that the construction andarrangement of the elements of the invention may be modified within thescope of the appended claims.

I claim:

1. A fireplace assembly comprising a firebox, a chimney means includinga first duct for conducting cold air into said fireplace assembly and asecond duct for exhausting heated air from said fireplace assembly,means for placing said firebox in communication with said chimney means,a single-walled housing means completely surrounding said firebox andsaid means for placing said firebox into communication with said chimneyand spaced therefrom defining passageways therebetween, first bafflemeans for directing cold air from said first duct down a first pair ofopposed sides of said firebox, second baffle means for directing heatedair from a second pair of opposed sides of said firebox upwardly throughsaid second duct, and third baffle means directing said air from each ofsaid first pair opposed sides to each of said second pair of opposedsides.

2. The fireplace assembly defined in claim 1 wherein said third bafflemeans directs air from one of said first pair of opposed sides to one ofsaid second pair of opposed sides and from the other of said first pairof opposed sides to the other of said second pair of opposed sides.

3. The fireplace assembly defined in claim 1 wherein said first pair ofopposed sides are the front and back sides of said fireplace and saidsecond pair of opposed sides are the right and left sides of saidfireplace.

4. The fireplace assembly defined in claim 1 wherein said first pair ofopposed sides are the right and left sides of the fireplace and saidsecond pair of opposed side are the front and back sides of saidfireplace.

5. The fireplace assembly defined in claim 2 wherein said said firstpair of opposed sides are the front and back sides of said fireplace andsaid second pair of opposed sides are the right and left sides of saidfireplace.

6. The fireplace assembly defined in claim 2 wherein said first pair ofopposed sides are the right and left sides of said fireplace and saidsecond pair of sides are the front and back sides of said fireplace.

7. A fireplace assembly adapted to cooperate with a chimney means havinga flue, a first annular duct for conducting cold air into said fireplaceassembly and a second annular duct coaxial with said first annular ductfor exhausting heated air from said fireplace assembly, said fireplaceassembly comprismg a firebox having a lateral opening in the frontportion thereof to receive combustibles and comprising a base membersupported on legs, opposed vertical sidewalls extending upwardly fromthe sides of said base member and rear vertical wall extending upwardlyfrom the rear of said base member,

a dome assembly communicating said firebox with said flue,

said dome assembly comprising an opposed pair of sidewalls inclineddownwardly and outwardly from said first annular duct to the sidewallsof said firebox, a rear wall inclined downwardly and rearwardly fromsaid second annular duct to said rear wall of firebox, and a front wallinclined downwardly and forwardly from said second annular duct to saidlateral opening,

single wall housing means completely surrounding said firebox and saiddome assembly and spaced therefrom in such a manner that passageways aredefined therebetween downwardly from said first annular duct across saidsidewalls of said dome assembly, upwardly from said rear wall of saidfirebox across said rear wall of said dome assembly, into said secondannular duct, upwardly from the front portion of said firebox acrosssaid front wall of said dome assembly into said second annular duct, andbeneath said firebox, and

first baffle means for directing a portion of the air flowing down saidsidewalls of said dome assembly to the front portion of said firebox andsecond baffle means for directing airflow from beneath said firebox tosaid rear wall of said firebox.

1. A fireplace assembly comprising a firebox, a chimney means includinga first duct for conducting cold air into said fireplace assembly and asecond duct for exhausting heated air from said fireplace assembly,means for placing said firebox in communication with said chimney means,a single-walled housing means completely surrounding said firebox andsaid means for placing said firebox into communication with said chimneyand spaced therefrom defining passageways therebetween, first bafflemeans for directing cold air from said first duct down a first pair ofopposed sides of said firebox, second baffle means for directing heatedair from a second pair of opposed sides of said firebox upwardly throughsaid second duct, and third baffle means directing said air from each ofsaid first pair opposed sides to each of said second pair of opposedsides.
 2. The fireplace assembly defined in claim 1 wherein said thirdbaffle means directs air from one of said first pair of opposed sides toone of said second pair of opposed sides and from the other of saidfirst pair of opposed sides to the other of said second pair of opposedsides.
 3. The fireplace assembly defined in claim 1 wherein said firstpair of opposed sides are the front and back sides of said fireplace andsaid second pair of opposed sides are the right and left sides of saidfireplace.
 4. The fireplace assembly defined in claim 1 wherein saidfirst pair of opposed sides are the right and left sides of thefireplace and said second pair of opposed side are the front and backsides of said fireplace.
 5. The fireplace assembly defined in claim 2wherein said said first pair of opposed sides are the front and backsides of said fireplace and said second pair of opposed sides are theright and left sides of said fireplace.
 6. The fireplace assemblydefined in claim 2 wherein said first pair of opposed sides are theright and left sides of said fireplace and said second pair of sides arethe front and back sides of said fireplace.
 7. A fireplace assemblyadapted to cooperate with a chimney means having a flue, a first annularduct for conducting cold air into said fireplace assembly and a secondannular duct coaxial with said first annular duct for exhausting heatedair from said fireplace assembly, said fireplace assembly comprising afirebox having a lateral opening in the front portion thereof to receivecombustibles and comprising a base member supported on legs, opposedvertical sidewalls extending upwardly from the sides of said base memberand rear vertical wall extending upwardly from the rear of said basemember, a dome assembly communicating said firebox with said flue, saiddome assembly comprising an opposed pair of sidewalls inclineddownwardly and outwardly from said first annular duct to the sidewallsof said firebox, a rear wall inclined downwardly and rearwardly fromsaid second annular duct to said rear wall of firebox, and a front wallinclined downwardly and forwardly from said second annular duct to saidlateral opening, a single wall housing means completely surrounding saidfirebox and said dome assembly and spaced therefrom in such a mannerthat passageways are defined therebetween downwardly from said firstannular duct across said sidewalls of said dome assembly, upwardly fromsaid reAr wall of said firebox across said rear wall of said domeassembly, into said second annular duct, upwardly from the front portionof said firebox across said front wall of said dome assembly into saidsecond annular duct, and beneath said firebox, and first baffle meansfor directing a portion of the air flowing down said sidewalls of saiddome assembly to the front portion of said firebox and second bafflemeans for directing airflow from beneath said firebox to said rear wallof said firebox.